Observation of the Coronal Hard X-ray Sources of the 1998 April 23 Flare

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Abstract
We analyzed Hard X-Ray Telescope observations of an X1.2 flare on 1998 April 23. This flare is one of the best examples for studying coronal hard X-ray sources due to the intensity of the emission and the occultation of the footpoints. In this flare, coronal hard X-ray sources composed of both thermal and nonthermal emissions showed complex structure unlike any previously observed. Dominant thermal and nonthermal sources do not come from the same loop-top region. Nonthermal sources include two sources in the low corona (~2.7 × 103 km) and an extended source in the high corona (~5 × 104 km). These observations of nonthermal coronal sources suggest that energetic phenomena occur in the low corona at first, and energized electrons are then injected into a high coronal region.

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